Checking the time during a nighttime hike or camping trip shouldn’t require reaching for a smartphone or switching on a headlamp. Traditional watches with luminous hands can help, but small hour markers aren’t always easy to distinguish in darkness. For people who regularly spend time outdoors after sunset, a more readable dial can make checking the time less disruptive.
Price: ¥61,600 (About $390)
Where to Buy: Casio Japan
The Casio PRO TREK PRW-51LD-1JF addresses this problem with a luminous dial that glows green after exposure to light. Scheduled for release in Japan in October 2026, the watch combines this distinctive feature with Triple Sensor technology, Tough Solar charging, and radio-controlled timekeeping. Priced at ¥61,600, it offers an alternative to connected smartwatches for buyers who prefer traditional controls and dedicated outdoor functions.
A glowing dial that makes nighttime reading easier
The PRW-51LD-1JF’s most distinctive feature is its luminous dial. Unlike conventional watches that illuminate only the hands and hour markers, Casio uses a larger luminous surface with prominent Arabic numerals.
After absorbing light from the sun or another source, the dial emits a green glow that makes the time easier to read in darkness. This allows wearers to check the time without immediately activating an electronic light, which can be useful when their eyes have adjusted to low-light conditions.
The glow gradually fades, however, and its brightness depends on how much light the dial has absorbed. It isn’t a continuously powered display, so visibility will vary depending on the conditions.
Casio also includes a full-auto double LED lighting system that illuminates both the analog dial and digital display. This provides another option when the luminous material is no longer bright enough to read comfortably.
Lightweight construction for outdoor activities
Outdoor watches often have substantial cases, but the PRW-51LD-1JF combines its relatively large dimensions with lightweight materials. It measures 51 × 47.4 × 14.5 mm and weighs approximately 55 grams, making it lighter than its size might suggest.
The case combines stainless steel and resin, while the soft urethane strap is designed to accommodate wrist movement. Casio also incorporates biomass plastics into several resin components, including parts of the case and strap.
The use of biomass plastic reduces reliance on conventional petroleum-derived materials in those components, although it doesn’t establish the overall environmental impact of manufacturing the finished watch.
Black ion plating on the bezel and exterior controls gives the watch a restrained appearance. Its predominantly black design also makes it suitable for everyday clothing, although the case dimensions may be less appealing to people who prefer smaller watches.
Mineral glass protects the dial, while 10-bar (100-meter-rated) water resistance provides protection during rain and swimming; the rating does not mean the watch is suitable for use at an actual depth of 100 meters. Casio also specifies low-temperature resistance down to -10°C, supporting use in colder outdoor environments.
Triple Sensor technology provides information on the trail
The PRW-51LD-1JF includes Casio’s Triple Sensor system, which measures direction, altitude, atmospheric pressure, and temperature.
Its digital compass helps users establish direction, while the altimeter estimates elevation using changes in atmospheric pressure. The barometer provides pressure readings that can help identify developing weather patterns, and the thermometer measures surrounding temperature.
These functions provide convenient wrist-based readings during hiking and camping trips, complementing dedicated navigation equipment when environmental conditions change quickly.
However, the sensors have limitations. Changes in atmospheric pressure can affect altitude estimates. For ambient-temperature readings, remove the watch from your wrist and keep it away from direct sunlight.
The PRW-51LD-1JF also doesn’t provide GPS positioning or turn-by-turn navigation. Its compass and environmental sensors are supplementary tools rather than replacements for maps, navigation equipment, or reliable weather forecasts.
Tough Solar charging and radio-controlled timekeeping
The PRW-51LD-1JF uses Casio’s Tough Solar system, which converts light into electrical energy to power the watch. This reduces the need for routine battery replacement and eliminates the frequent charging associated with many smartwatches.
Casio rates runtime without further light exposure at approximately six months with functions in use, or approximately 25 months while in the power-saving state.
Multi Band 6 radio-controlled timekeeping provides automatic time calibration when compatible signals are available. The system supports transmitters serving regions including Japan, North America, Europe, and China.
Reception depends on geographic coverage and surrounding conditions, so automatic synchronization isn’t guaranteed everywhere. When radio reception is unavailable, the watch continues operating as a quartz timepiece, with Casio specifying an average accuracy of ±15 seconds per month.
These features are particularly relevant for buyers who want a watch that requires relatively little attention between outdoor trips. With sufficient light exposure, solar charging can keep the watch running, while radio synchronization can reduce manual time adjustments in supported locations.
Useful functions beyond hiking and camping
Although the PRW-51LD-1JF belongs to Casio’s outdoor-focused PRO TREK collection, its functionality extends beyond hiking and camping.
The watch includes world time covering 29 cities, a stopwatch, countdown timer, five daily alarms, and an automatic calendar. Its combination of analog hands and a digital display allows users to access these functions without relying on a touchscreen.
World time is useful for international travel, while the alarms and countdown timer can serve everyday scheduling needs. The analog-digital layout also provides access to sensor information while retaining the appearance of a conventional wristwatch.
Unlike connected smartwatches, the PRW-51LD-1JF doesn’t offer smartphone notifications, downloadable maps, or fitness tracking. Its focus remains on timekeeping and environmental measurements rather than connected applications.
Who should buy the Casio PRO TREK PRW-51LD-1JF?
For overnight campers and early-start hikers, the Casio PRO TREK PRW-51LD-1JF pairs a light-charged luminous dial with outdoor sensors, lightweight construction, and traditional button controls. With sufficient light exposure, Tough Solar keeps it running without a smartwatch-style charging routine.
Price: ¥61,600 (About $390)
Where to Buy: Casio Japan
At ¥61,600 including tax in Japan, the draw is that glowing dial alongside familiar PRO TREK functionality. If nighttime readability isn’t a priority, consider another PRO TREK model. If you need GPS navigation or connected features, look to an outdoor smartwatch.
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